The present invention is directed to a system for the continuous treatment of a steel strip in a liquid treating tank. More particularly, the invention is directed to an apparatus for the continuous pickling of a steel strip.
Numerous pickling tanks have been developed for pickling sheet steel in a continuous process. Many of these pickling tanks include a shallow pickling bath where the continuous steel strip is pulled through the bath of pickling acid. Spray nozzles are also used to supply a continuous stream of pickling acid to the steel strip.
Many pickling processes use a plurality of pickling tanks arranged in series. The continuous steel strip is carried through each tank in successive stages to attain the desired pickling effect. The pickling tanks typically include a suitable device for removing excess pickling acid from the steel strip as the steel strip is removed from each successive bath. For example, pressing rollers are often used at each end of a pickling tank to guide the steel strip through the pickling acid and remove the excess pickling acid from the strip. An example of this type of pickling tank is disclosed in U.S. Pat. No. 5,800,694 to Starcevic et al.
Another example of a pickling tank is disclosed in U.S. Pat. No. 5,566,694 to Pugh et al. The pickling tank includes two end stands spaced apart from each other and secured to a foundation. A trough containing a pickling acid extends between the two stands and is anchored at the center. The stands at each end of the trough include pressing rollers to guide the steel strip. An expandable seal connects each end of the trough with each stand to allow for thermal expansion of the trough relative to the stands. The expandable seal is formed from several spaced apart baffles allowing some movement between the trough and the stand.
Recently, there has been an increase in interest in producing pickling tanks made of a synthetic material that are resistant to attack by the pickling acids. However, tanks made from synthetic materials often are not sufficiently strong to contain the weight of the pickling bath and the steel strip. As a result, the pickling tanks can sag and deform due to the weight of the pickling acid and the temperature of the acid bath. In addition, the end chambers of the bath when made from a synthetic material often deform causing leaking of the pickling acid. It is very difficult to control the flow of the pickling acid in these devices because the liquid level in the pickling bath is above the seal between the pickling tank and the end chamber.
The present invention is directed to a pickling tank for treating a continuous steel strip. More particularly, the invention is directed to a pickling tank assembly having an expandable linkage to prevent leaking of pickling acid.
Accordingly, a primary object of the invention is to provide a pickling tank having a sealing assembly for containing the pickling acid.
Another object of the invention is to provide a pickling tank having a sealing assembly at each end where the liquid level in the pickling tank is independent of the sealing assembly.
A further object of the invention is to provide a pickling tank for a steel strip where the liquid level in the pickling tank can be adjusted independent of the sealing assembly.
Another object of the invention is to provide a pickling tank having a pickling trough and a separate pickling acid recovery tank spaced from the pickling trough.
Still another object of the invention is to provide a pickling tank having a pickling trough and a pickling acid recovery tank where the recovery tank includes two opposing pressing rollers for removing pickling acid from a steel strip.
A further object of the invention is to provide a pickling tank having a pickling trough and a separate pickling acid recovery tank where a primary acid recirculating loop takes place only in the pickling trough.
A further object of the invention is to provide a pickling tank having a pickling trough and a pickling acid recovery tank having two opposing pressing rollers and a chute connecting the pickling trough with the recovery tank where the chute allows limited movement between the pickling trough and the recovery tank.
Another object of the invention is to provide a pickling tank including a pickling trough and a pickling acid recovery tank coupled together by a chute that is able to accommodate for thermal expansion between the pickling trough and the recovery tank.
A further object of the invention is to provide a pickling tank made of a synthetic material that is resistant to corrosion attack by a pickling acid.
Another object of the invention is to provide a pickling tank having an overflow tray made of a synthetic material, a pickling trough and a pickling acid recovery tank where the pickling trough is positioned on the tray.
A further object of the invention is to provide a pickling tank having a pickling trough, a pickling acid recovery tank having two opposing pressing rollers and a chute having a first end connected to the pickling tank and a second end forming a seal against the rollers.
The objects of the invention are basically attained by providing a pickling tank for pickling a continuous strip. The pickling tank comprises a pickling trough for containing a pickling solution. The pickling trough has a bottom wall, a first end wall at a first end of the trough and a second end wall at a second end of the trough. The first end wall has an inlet for the continuous strip and the second end wall has an outlet for the continuous strip. A pickling solution recovery tank has an inlet, an outlet and two opposing pressing rollers positioned in the recovery tank. The recovery tank is spaced from and coupled to the pickling trough.
The objects of the invention are further attained by providing a pickling tank for pickling a continuous steel strip. The pickling tank comprises a pickling trough having a pickling bath area with a first end and a second end. The pickling trough is dimensioned for containing a pickling solution. The pickling trough has a pickling solution discharge trough at the first end of the pickling trough for receiving overflow pickling solution from the pickling bath area. A pickling solution recovery tank has two opposing pressing rollers positioned in the recovery tank for removing pickling solution from a steel strip passing through the tank. A chute has a first end coupled to the discharge trough and a second end coupled to the recovery tank. The chute is coupled to the discharge trough and the recovery tank to allow limited movement between the discharge trough and recovery tank.
The objects, advantages and salient features of the invention will become apparent to one skilled in the art in view of the following detailed description of the invention, taken in conjunction with the annexed drawings which form a part of this original disclosure.